1In a blender or food processor, grind the ginger root, garlic, cashews, lemon grass, and onions into a paste.
2Heat olive oil in a medium wok over low heat. Stir in the blended mixture and red pepper flakes. Gradually mix in the curry powder.
3Place tofu in the wok, and cook until heated through. Mix in the coconut milk, water, and potatoes. Bring to a boil, reduce heat, and simmer 20 minutes, stirring occasionally, until potatoes are tender. Season with salt and sugar.